Numerous attempts have been made to provide, typically for a pick-up truck, a carriage which fits into the rear box when stowed, and which is associated with a mechanism by which the carriage can be removed from the truck box and set down upon the same surface as that supporting the truck. Such carriages range in use from garbage collecting to the transportation of vehicles such as skidoos or of bulk materials. Generally, the prior art has attempted to over-engineer the various frame members supporting the carriage during its movement, often utilizing several parallelogram linkages, winches and cables, and thus having to deal with the problem of disengaging complex supporting linkages from the carriage, once the carriage is on the ground. These prior carriage-handling mechanisms have been expensive, unreliable and time-consuming to install and maintain, as well as requiring professional operators trained on the sequencing of various controls, sometime in unison, during carriage retraction and deployment.
In addition, prior carriage-handling mechanisms designed for use in pick-up trucks have a high centre-of-gravity when the carriage is in the stowed position. For example, U.S. Pat. Nos. 6,152,674, 5,232,329 and 5,620,296 each describe mechanisms that position the carriage at a level that is at or above the rear box, resulting in a high centre-of-gravity. This can severely affect the controllability of the vehicle, resulting in a safety issue, especially during accident avoidance manoeuvres.